[masklinn]

As indicated in the second note, in CPython (2.7 or 3.4) it's roughly the same as the eager version. In pypy the lazy version is about 3 times slower than the eager version.

Version from your post:

    > time python2.7 test_eager.py                           
    [(9567, 1085, 10652)]
    python2.7 test_eager.py  6.41s user 0.02s system 99% cpu 6.451 total
    > time python3.4 test_eager.py                           
    [(9567, 1085, 10652)]
    python3.4 test_eager.py  6.28s user 0.03s system 99% cpu 6.372 total
    > time pypy test_eager.py                                
    [(9567, 1085, 10652)]
    pypy test_eager.py  0.95s user 0.06s system 98% cpu 1.022 total

Using `yield from` (3.4-only) and wrapping the solutions() call in a `list()`:

    > time python3.4 test_yield.py                    
    [(9567, 1085, 10652)]
    python3.4 test_yield.py  6.28s user 0.02s system 99% cpu 6.313 total

Using chain.from_iterable + imap (or map in 3.4) and wrapping the solutions() call in a `list()`:

    > time python2.7 test_imap.py                    
    [(9567, 1085, 10652)]
    python2.7 test_imap.py  6.52s user 0.02s system 99% cpu 6.558 total
    > time python3.4 test_imap.py                    
    [(9567, 1085, 10652)]
    python3.4 test_imap.py  6.26s user 0.02s system 99% cpu 6.292 total
    > time pypy test_imap.py                    
    [(9567, 1085, 10652)]
    pypy test_imap.py  2.87s user 0.06s system 99% cpu 2.943 total

Versions used: Python 2.7.10, Python 3.4.3, PyPy 2.6.0 with GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57); all from macports